Hydrolysis system and method for a vehicle engine

ABSTRACT

A hydrolysis system and expansion tank includes an electrolysis unit that produces a fuel gas including hydrogen and oxygen by electrolysis; an expansion tank having an interior cavity that expands the fuel gas; and a heating element that heats the fuel gas. The heating element may include a conduit within the interior cavity for circulating hot water. A device for providing fuel gas includes a gas input line adapted to receive a fuel gas; an expansion tank having an interior cavity that is significantly larger than the gas input line so that the fuel gas expands within the cavity; and a conduit adapted to circulate a hot water thereby heating the fuel gas. Embodiments may include a method for providing fuel includes utilizing an electrolysis unit to produce a fuel gas that includes hydrogen and oxygen; expanding the fuel gas; and heating the fuel gas with circulating hot water.

RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S. PatentApplication No. 61/814,033, filed Apr. 19, 2013, (B012-102), which isincorporated herein by reference in its entirety; and U.S. patentapplication Ser. No. 14/257,989, filed Apr. 21, 2014, (B012-103), whichis incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention generally relates to electrolysis systems and morespecifically to a hydrolysis system and expansion tank.

Existing internal combustion engines for automobiles may burn only 20%of the carbon in the gasoline or diesel fuel. Carbon is sent to acatalytic converter, which is wasteful, and produces emissions thatinclude noxious gasses and green house gasses, such as carbon monoxide(CO), carbon dioxide (CO2), and nitrous oxide (NO). The use of on-boardelectrolysis in producing small amounts of hydrogen and oxygen gassesinto the air intake of an internal combustion engine may increasemileage and reduce emissions from the automobile.

Existing automobiles with electronic fuel injection (EFI) have an enginecontrol unit (ECU), which is a computer that reads values from sensorsand provides signals to adjust or control the engine. Traditional airintake boxes for an automobile air box keeps the air clean by removingparticles with a filter, but do not warm the air. When the air is cold,mileage drops because the denser air mass causes the automobile's ECUcomputer (or an independent control system) to put more fuel into theengine.

It would be therefore be desirable to have a device that may be usefulto an individual, business or corporation who desires or needs areduction in fuel consumption and has a desire to reduce emissions, suchas, for example trucking companies, police departments, school systems,individuals who commute to and from work, and others who wish to reduceemissions.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a device includes anelectrolysis unit that produces a fuel gas including hydrogen and oxygenby electrolysis; an expansion tank having an interior cavity thatexpands the fuel gas; and a heating element that heats the fuel gas. Theheating element may include a conduit within the interior cavity of theexpansion tank for circulating hot water.

In another aspect of the present invention, a device for providing fuelgas includes a gas input line adapted to receive a fuel gas; anexpansion tank having an interior cavity that is significantly largerthan the gas input line so that the fuel gas expands within the cavity;and a conduit adapted to circulate a hot water thereby heating the fuelgas.

In yet another aspect of the present invention, a method for providingfuel includes utilizing an electrolysis unit to produce a fuel gas thatincludes hydrogen and oxygen; expanding the fuel gas; and heating thefuel gas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic of an embodiment of a hydrolysis fuel gasunit according to the present invention;

FIG. 2 depicts an electrolysis unit according to the embodiment of FIG.1;

FIG. 3A depicts a front faceplate according to the embodiment of FIG. 1;

FIG. 3B depicts a rear faceplate according to the embodiment of FIG. 1;

FIG. 3C depicts a central plate according to the embodiment of FIG. 1;

FIG. 4 depicts a first embodiment of an air box according to the presentinvention;

FIG. 5 depicts a second embodiment of an air box according to thepresent invention; and

FIG. 6 depicts a hydrolysis system according to the embodiments of FIG.1 and FIG. 4.

DETAILED DESCRIPTION

The preferred embodiment and other embodiments, which can be used inindustry and include the best mode now known of carrying out theinvention, are hereby described in detail with reference to thedrawings. Further embodiments, features and advantages will becomeapparent from the ensuing description, or may be learned without undueexperimentation. The figures are not necessarily drawn to scale, exceptwhere otherwise indicated. The following description of embodiments,even if phrased in terms of “the invention” or what the embodiment “is,”is not to be taken in a limiting sense, but describes the manner andprocess of making and using the invention. The coverage of this patentwill be described in the claims. The order in which steps are listed inthe claims does not necessarily indicate that the steps must beperformed in that order.

An embodiment of the present invention generally provides a hydrolysissystem and method for a vehicle engine.

Embodiments of the present invention generally include a hydrolysissystem or unit that produces a gas (referred to herein as “fuel gas”)for a vehicle engine, such as an internal combustion engine for anautomobile or truck. Embodiments may be self-contained units that areconnected to an automobile or other vehicle's battery and engine airintake. Applications are on the highway, marine, air, andconstruction/industrial. Embodiments may utilize on-board electrolysisto provide hydrogen gas or other gasses to the engine. This injection ofhydrogen (aka HHO injection) may help burn automobile fuel (such asgasoline or diesel fuel) that is otherwise exhausted, and thereforeimprove mileage and reduce emissions. The system contributes to a cleanburn in the cylinder of the internal combustion engine, providesancillary energy to the vehicle, and may reduce noxious emissions.Embodiments may be provided as an add-on or may be already-installed ina vehicle.

Embodiments of a hydrolysis cell may produce a fuel gas that includesgaseous hydrogen (H2), oxygen (O2), and ammonia (NH3). The H2 and O2provide desirable negative and positive ions, respectively. The ammoniain the fuel gas may exist as an aerosol, and the hydrogen and oxygen asvapor. The fuel gas rises from the hydrolysis cell and is pumped into atank that may also contain a reserve of electrolyte including ammonia.The fuel gas is piped out of the reservoir, further treated (dried,heated, expanded, and atomized), piped out of the hydrolysis system, andmixed into the air source for the automobile engine. Embodiments mayemploy the Venturi effect to help empty the electrolysis system of fuelgas and provide it to the automobile's air intake manifold. Liquidammonia and water should be added to the system by the user when neededto replenish these materials as they are consumed.

In conjunction with or independent from the hydrolysis system, anembodiment of an air box heater heats the fresh air into theautomobile's air intake manifold. This may help the engine start on colddays, may improve mileage, and in conjunction with the hydrolysis systemmay enhance the engine's utilization of the fuel gas to provide an evengreater improvement in mileage.

As depicted in the embodiment of FIG. 1, a hydrolysis fuel gas unit 10may include an electrolysis unit 18, which is a hydrogen production cellcontaining electrolyte and hydrolysis plates. The electrolysis unit 18provides fuel gas to an electrolyte tank 20. Condensed and reserveelectrolyte 26 is returned from the electrolyte tank 20 to theelectrolysis unit 18 via a circulation pump 22. Both the electrolysisunit 18 and the pump 22 may be controlled by a pulse width modulator 16powered by the vehicle battery. Fuel gas in the electrolyte tank 20 maybe kept under pressure, and when demanded, fuel gas is provided througha dryer 38 and an expansion tank 50, warmed, and output from a spraytube 64.

An embodiment of a hydrolysis fuel gas unit 10 may receive power throughfrom an external power source 52, such as a 12-volt automobile batteryor a dry cell. Embodiments of a pulse width modulator (“PWM”) 16 mayprovide power to the electrolysis unit 18 through electrolysis powerlines 54, and through pump power lines 48 to an electrolyte circulationpump 22. PWM 16 allows the user to control the amperage allowed to anelectrolysis unit 18, so that the system does not come on until thealternator is in operation.

In embodiments, when the engine is idle, PWM 16 may allow only arelatively small amount of current, such as for example 8 amps, toproduce only a relatively small amount of fuel gas. When the vehicleaccelerates, PWM 16 will provide more current which in turn creates moreHydrogen. This may be desirable, because the engine is drawing moregasoline and the system is adding automobile fuel gas when it is reallyneeded. Embodiments may create a balance of fuel mixture, whether atidle or during acceleration.

In an embodiment for turbo-diesel automobile engines (not shown), apressure switch may provide a signal to the PWM 16. The switch may bepositioned on the pressure side of a turbo and may have at least twomodes to set different amperages in PWM 16. If the pressure is less thana preset amount, for example 20 psi, then the switch is in a lowposition and PWM 16 will output a low preset amount of current toprovide a relatively low rate of hydrolysis in the electrolysis unit 18.When the pressure his higher, the switch is high for a higher rate ofhydrolysis. This may be especially helpful when starting the engine orin cold weather.

An electrolysis unit 18 may be a fuel cell or hydrogen-cell thatutilizes an electrolyte such as ammonia for hydrolysis. Gaseoushydrogen, oxygen, and aerosol electrolyte (including aerosol ammonia)from the electrolysis unit 18 may be delivered through an HHO gas inline 34 to an electrolyte tank 20 or other reservoir. The electrolytetank 20 is a reservoir for liquid reserve electrolyte 26 and droplets ofelectrolyte that condense out of the fuel gas, and it also storespressurized gaseous fuel gas so the fuel gas can be output from thesystem when needed.

The fuel gas may bubble up through the reserve electrolyte 26 and becollected within the upper portion of the airtight electrolyte tank 20.The electrolyte tank 20 may be bolted or otherwise mounted to a vehicle,and may have a removable cap 24 on the top so that electrolyte and watermay be added as needed. To ensure safety, electrolyte tank 20 maycontain a float switch 30, and when the switch 30 detects that thereserve electrolyte 26 in the tank falls to 15% or less, the entirehydrolysis unit may shut off. The electrolyte may have an alkaline PH,such as ammonia with PH 12, combined with water.

Condensed liquid electrolyte and reserve electrolyte 26 in theelectrolyte tank 20 may be returned to the electrolysis unit 18 asneeded using a circulation pump 22 that may run continuously duringoperation. The electrolyte circulation pump 22 may pump liquid from theelectrolyte tank 20 to the electrolysis unit 18 through an electrolysisrecharge line 32. This may help blow the bubbles of hydrogen and oxygenoff of the plates in the electrolysis unit 18, as well as help providepressure and urge the mixture of hydrogen, oxygen, and electrolyte topass through the fuel gas lines. Ammonia and distilled water may beprovided to the electrolyte tank 20 as needed to top off the reserveelectrolyte 26 utilizing a removable and replaceable cap 24. The pumpmay receive power through pump power lines 48 from the PWM 16.

Embodiments may include a dryer 38 that dries the fuel gas through afilter. The dryer 38 is positioned either just before or inside of theexpansion tank 50. The gas passes from the electrolyte tank 20 via anHHO gas out line 36 to the dryer 38, and the filter removes moisturefrom the gas. Embodiments of a filter may be a 5 micron nylon clothfiber or other mesh filter. The filter fills a cross section of thedryer 38 so that fuel gas passing through the dryer 38 passes throughthe filter.

In a first embodiment as depicted in FIG. 1, fuel gas from a separatedryer 38 may be provided through a dried fuel gas line 42 to theexpansion tank 50.

In a second embodiment (not shown), the dryer 38 and its filter arelocated immediately inside the expansion tank 50, the HHO gas out line36 feeds directly into the expansion tank 50, and a separate dried fuelgas line 42 is unnecessary.

Expansion tank 50 may have a chamber 60 that is larger than the inputfuel line, so the gas expands. Expansion tank 50 may also be a gasheater or warmer, and have a hot water input 56 that receives hot waterfrom the radiator, a hot water conduit 62 or pipe that goes through thetank carrying the hot water, and a hot water output 58 that returns thewater back to the radiator. The hot water passes through the hot waterconduit 62 inside expansion tank 50, and the fuel gas from the driedfuel gas line 42 (or HHO gas out line 36) is warmed by passing over thehot water conduit 62 in an air-tight chamber 60 formed by the walls ofthe expansion tank 50. The fuel gas expands because the chamber 60 islarger than the input fuel gas line. The expansion increases thevolatility of the existing hydrogen ions and produces additionalhydrogen ions from the reaction of heat with ammonia gas. The heat warmsthe air in the chamber 60, so that the volatility of H ions ismaintained. The heat also removes moisture from the fuel gas to helpprevent water and ammonia from going into the engine. The hot waterconduit 62 may be a straight tube, a coiled tube, or other liquid-tightpassageway made of heat-conductive material such as copper.

When the automobile accelerates, the air intake of the engine increasesvacuum pressure, which draws more automobile fuel and also draws morefuel gas from the fuel gas expansion tank. The hydrolysis unit builds uppressure of fuel gas, and then when the automobile accelerates, theengine may naturally draw more fuel gas into the engine. In embodiments,no additional pumps are needed to transport the fuel gas from thehydrogen production cell to the engine air intake.

After expansion tank 50 allows the gas to expand, the fuel gas may thenbe sent through a hot expanded fuel gas line 68 to a spray tube 64 oratomizer, which then feeds the fuel gas to the air intake of thevehicle's engine. This may help maintain the volatility of the Hydrogenions. Embodiments may have differently sized pores 66 or perforations onthe spray tube 64 for different types of internal combustion engine.Different types of engines may require a specific diameter and number ofpores 66 in the spray tube 64, such as for example 4 pores, with smallerholes for smaller engines.

In embodiments, the tubes or conduit for transmitting fuel gas from theelectrolysis unit 18 to the expansion tank 50 (namely, lines 34, 36, and42) may have a first, larger diameter such as for example ⅜″, and thelast fuel gas conduit (line 68) may have a smaller diameter such as forexample ¼″. This may allow pressure to build up in expansion tank 50 andthe rest of the hydrolysis fuel gas unit 10, which increases thevelocity of external fuel output 40 that is fed to the air intake of theengine.

In embodiments, the fuel gas conduits (lines 34, 36, 42 and 68) mayfurther include a conduit constricting element 70 at one or both ends.The orifices at each junction are restricted by the conduit constrictingelements 70 so that the fuel gas stream passes from an area of higherpressure to low pressure at each junction, and therefore flows at ahigher velocity.

As depicted in the embodiment of FIG. 2, an electrolysis unit 18 mayinclude a plurality of spaced, generally parallel, generally circularhydrolysis plates 80 separated by electrolyte. The plates 80 may behighly conductive, and may be made of silicon, stainless steel, nickel,silicone, and/or conductive plastic (polymer). Embodiments of anelectrolyte may be a liquid rich in ions, and preferably ammonia. Theelectrolysis unit 18 receives pulsed DC electric current from PWM andapplies it to the hydrolysis plates 80 so that they produce fuel gas.

The plates 80 may be organized as −NN+NN−, with negative front and rearfaceplates 82, 86 electrically connected to a negative lead, a positivecentral (or nearly central) plate 96 electrically connected to apositive lead, and with two neutral plates 102 between each positive andnegative plate. The neutral plates 102 may help control the voltage orpotential from plate to plate. Adding plates will reduce the totalvoltage drop per plate, to help reduce heat and improve efficiency atlow amperage. Other embodiments may include up to 10 plates in variousconfigurations, such as −NN+NN+NN− (with two central interior plateshaving the same polarity connections) or +NN−NN+ (swapping the positiveand negative connections).

In an embodiment, the interior plates 84 (all the plates except thefront faceplate 82 and the rear faceplate 86) have a relatively small,round, lower aperture 88 or round hole near the bottom and a larger,crescent-shaped, upper aperture 90 or hole near the top. When installedin the electrolysis unit 18, the apertures 88, 90 of the interior plates84 align with each other and form straight passages that allow fluids toflow through. The upper, larger aperture 90 allows the fuel gas thataccumulates to pass through the interior plates 84, and the lower,smaller aperture 88 is to pump and recirculate the ammonia or otherelectrolyte through the electrolytic cells. The upper aperture 90 mayhave a generally flat lower edge, parallel with and above the level ofthe liquid electrolyte, and the upper edge may form an arc that conformsto the outer rim of the circular plates 80. The upper aperture's shapemay utilize otherwise wasted space on the electrolysis plates may helpremove all of the fuel gas from the hydrolysis unit without heating upthe system, so that the system runs cooler and produces more fuel gas atlower currents.

The outer front and rear faceplates 82, 86 may have bolt holes 92 on thefar outside edge of each faceplate 82, 86, such as 12 equally-spacedbolt holes 92, so they can be electrically connected with conductivebolts 94 through electrolysis power lines 54 to a negative lead from thePWM. The faceplates 82, 86 have a larger radius than the interior plates84, so that the interior plates 84 do not come in contact with thenegatively-connected conductive bolts 94

As depicted in FIG. 3A, an embodiment of a front faceplate 82 may have alower fitting 108 and an upper fitting 110. The lower fitting 108 alignswith the lower (round) apertures in the interior plates, and the upperfitting 110 aligns with the upper (crescent-shaped) apertures in theinterior plates. The lower fitting 108 receives electrolyte from theelectrolysis recharge line 32 and provides it into the lower apertures,to wash over all the hydrolysis plates, and the upper fitting 110receives fuel gas from the upper apertures and provides it out of theelectrolysis unit and into the electrolysis gas line 34.

As depicted in FIG. 3B, an embodiment of a rear faceplate 86 may have amounting bracket or flange 106 with mounting holes to help mount theelectrolysis unit in a vehicle near the engine. The rear faceplate 86may be a solid piece, to form an air and water-tight end for theelectrolysis unit. If the rear faceplate 86 is mounted directly to themetal frame of a vehicle, the faceplates will become “grounded” to thevehicle, so may be desirable for the faceplates to be powered withnegative voltage if the vehicle battery negative lead is also groundedto the frame.

As depicted in FIG. 3C, an embodiment of a central plate 96 ornearly-central interior plate may have an electrical connection tab 98with an electrical connection aperture 100 that extends from the plate'srim and between the conductive bolts of the outer faceplates so that thetab 98 can be electrically connected with a bolt or wire throughelectrolysis power lines 54 to a positive lead from the PWM. Embodimentsmay have a second central, positive interior plate, with the positiveplates separated by additional neutral plates. The central plate 96 is“central” in that some embodiments have a single central plate in themiddle (such as a −NN+NN− configuration), but other embodiments may have2 positively-charged central plates 96 (such as a −NN+NN+NN−configuration).

The remaining interior plates 84 may be neutral plates 102, notconnected to any power source. They should have the same radius as thecentral plate 96, but without any electrical connection tab. All theinterior plates 84 including the central plate 96 have matching lowerapertures 88 and crescent-shaped upper apertures 90.

The hydrolysis plates 80 may all be “generally circular” in that theyare either a disk (such as the front faceplate 82 and the neutral plates102), or they have a circular disk-like portion with extensions (such asthe rear faceplate 86 having a mounting flange 106, and the centralplate 96 having an electrical connection tab 98). The plates may be“generally parallel” in that they have flat surfaces for electrolysisthat are stacked face-to-face but do not touch each other.

The hydrolysis plates 80 may have gaskets 104 between them, to provide awater and gas-tight seal between the plates 80, yet allow theelectrolyte to bathe the spaces between the plates 80 for electrolysis.The gaskets 104 may include rubber or other elastic rings around theedges of the plates. The size of the gaskets 104 may vary according tothe size of the unit, such as from 3/32″ to ⅛″ in thickness and ofappropriate diameter to match the plates 80. The electrolysis plates 80themselves may provide the housing for the electrolysis unit 18.

Embodiments may include an air warmer inside a heated automobile air box110 that heats the air before it flows into the automobile air intakemanifold. This may help start the engine on cold days and increasemileage. Cold air passes into the air box 110, perhaps near the bottom,becomes warmed, passes through the automobile's air filter, and then thewarm air passes out of the air box, perhaps near the top. The heated airthen passes to the air intake manifold of the automobile. The warmer airmass may allow the vehicle's ECU to cut back and run more efficiently,especially in cold temperatures.

As depicted in FIG. 4, in a first embodiment, an air box 120 has ahalogen lamp 122 or other heating element and a thermostat 124. The lamp122 and thermostat 124 are powered by the automobile battery 12. Thethermostat 124 is positioned at a distance from the lamp 122 so thatthat the thermostat 124 can measure the temperature of the air in aportion of the air box and provide a signal to the lamp 122 to controlwhether the lamp 122 is on or off. Fresh, cold air enters through an airbox intake 130, flows around and past the lamp 122 to become heated,continues through the air filter 132, and flows out an air box output134.

As depicted in FIG. 5, in a second embodiment, an air box 140 has a hotwater inlet 142 and hot water outlet 144 that receives and returns hotwater from the automobile's radiator. The hot water circulates throughan air heater conduit 146, which may include of a U-shaped tube made ofheat-conductive material such as copper. Fresh, cold air enter entersthrough an air box intake 130, flows around and past the air heaterconduit 146 to become heated, continues through the air filter 132, andthen flows out an air box output 134. A shut-off system (not shown) mayalso be provided to shut off the air heater when the air is hot, such ason a summer day.

In either embodiment, if any ammonia not yet converted to hydrogen, thenthe warming of the cold air may accelerate the development of hydrogengas. This may also dilute the air, so that the ECU cuts back.

As depicted in FIG. 6, an embodiment of a hydrolysis system for avehicle engine 150 may include a hydrolysis fuel gas unit 10 and aheated automobile air box 120, both connected to the air intake manifold150 of an automobile. The pulse width modulator of the hydrolysis fuelgas unit 10 is connected to the automobile battery 12, and for a halogenlamp embodiment of a heater air box, the lamp is also connected to theautomobile battery 12. Other embodiments may use the hot waterembodiment of an air box 140. The air box 120 provides heated fresh airand the hydrolysis system 150 simultaneously provides fuel gas to theair intake of the vehicle.

An embodiment of a method for preparing a hydrolysis fuel gas unit mayinclude:

providing hydrolysis plates having upper and lower apertures, such as alower, round aperture for electrolyte and an upper, crescent-shapedaperture for fuel gas;

washing the hydrolysis plates in vinegar or acetic acid;

allowing the plates to air dry;

wiping the plates down with acetone, in order to help remove any oilperhaps from the manufacturer;

assembling the hydrolysis fuel gas unit, such as by aligning theinterior plates and gaskets between outer faceplates and connecting thefaceplates with conductive bolts;

after assembling the unit, pumping and recirculating citric acid atbetween 140 and 160° F., preferably 150° F. degrees, through alignedupper and lower apertures of the plates for 8 to 12 minutes, preferably10 minutes; and

allowing the system to air dry.

This may help take the excess iron and loose iron fragments out ofstainless steel plates. When used in a hydrolysis system for anautomobile, this may help prevent discoloring because there is little orno excess iron to rust.

Embodiments may include a device for producing a fuel gas to a vehiclehaving an engine with an air intake and a radiator, comprising anelectrolysis unit that retains an electrolyte and produces a fuel gas; areservoir to contain the fuel gas and electrolyte provided from theelectrolysis unit; an electrolyte pump that returns electrolyte from thereservoir to the electrolysis unit; an expansion tank that receives thefuel gas and which includes an interior cavity adapted to carry hotwater from the radiator of the vehicle, to expand the fuel gas; a spraytube that feeds the fuel gas from expansion tank to the air intake ofthe vehicle's engine; and a pulse width modulator that providespulse-width-modulated power to the electrolysis unit and the electrolytepump. In embodiments, the electrolyte includes ammonia, and the fuel gasincludes gaseous hydrogen, gaseous oxygen, and gaseous ammonia.

I claim:
 1. A device comprising: an electrolysis unit that produces a fuel gas including hydrogen and oxygen by electrolysis; an expansion tank having an interior cavity that expands the fuel gas; and a heating element that heats the fuel gas.
 2. The device of claim 1, wherein the heating element is inside the interior cavity of the expansion tank.
 3. The device of claim 1, wherein the heating element includes circulating hot water.
 4. The device of claim 1, wherein the heating element includes a conduit within the interior cavity of the expansion tank for circulating hot water.
 5. A device for providing fuel gas, comprising: a gas input line adapted to receive a fuel gas; an expansion tank having an interior cavity that is significantly larger than the gas input line so that the fuel gas expands within the cavity; and a conduit adapted to circulate a hot water thereby heating the fuel gas.
 6. The device of claim 5, wherein the conduit is within the interior cavity of the expansion tank.
 7. The device of claim 5, wherein the fuel gas includes hydrogen and oxygen created by an electrolysis unit.
 8. The device of claim 5, further comprising: an electrolysis unit that produces fuel gas including hydrogen and oxygen and provides the fuel gas to the gas input line.
 9. A method for providing fuel gas, comprising: utilizing an electrolysis unit to produce a fuel gas that includes hydrogen and oxygen; expanding the fuel gas; and heating the fuel gas.
 10. The method of claim 9, wherein the fuel gas is expanded with an expansion tank, and the fuel gas is heated while the fuel gas is within the expansion tank.
 11. The method of claim 9, wherein the fuel gas is expanded within an expansion tank, and the fuel gas is heated with hot water that circulates through a conduit inside the expansion tank. 